1. Field of the Invention
The present invention relates to a semiconductor device, having a chip-size package structure, and a process for producing the same.
2. Description of the Related Art
A process for producing semiconductor devices comprising assembling semiconductor devices in the wafering step has been developed (Japanese Unexamined Patent Publication (Kokai) No. 10-79362). The process can provide semiconductor devices each having a separate chip-size package structure completed by cutting, and reduce the production costs.
The production process comprises forming a wiring pattern (rewiring pattern), to be connected to electrodes of the semiconductor chip, on an insulating film formed on the semiconductor chip, forming protruded electrodes by plating the wiring pattern, forming a protective film covering the wiring pattern by compression molding, and forming a solder bump for external connection on the end portion of each of the protruded electrodes.
The step of forming a protective film comprises the following procedures.
That is, a top face and a bottom face are heated to about 175.degree. C. A temporary film is absorbed by the top face.
A wafer on which a wiring pattern and protruded electrodes are formed is placed on the bottom face, and a sealing resin is placed on the wafer.
The resin is melted by the heat and pressure of the sealing mold to be spread over the entire wafer, and held within the mold to be cured.
The wafer is taken out of the mold, and the temporary film is peeled off.
A solder bump for external connection is formed on the end portion of each of the protruded electrodes.
However, the conventional process for producing a semiconductor device has been found to have the following problems.
That is, when the process is carried out by compression molding wherein a resin is placed on a wafer, the resin is melted by pressing the resin with a mold, and the molten resin is spread over the entire wafer to form a protective film, the protective film is also placed on the end face of each of the protruded electrodes, and removal of the protective film from the end face becomes incomplete.
Accordingly, when a solder bump 12 is bonded to the end portion of a protruded electrode 10 as shown in FIG. 16, the bond area of the solder bump 12 is reduced by a protective film 14, and the bond strength becomes insufficient, which causes a problem in reliability.
Moreover, the bonded portion of the solder bump 12 makes an acute angle with the surface of the protruded electrode 12, which causes the problem that the bump tends to be easily removed by impact.
In addition, the reference numerals 15, 16 and 18 designate a semiconductor chip, an insulating film formed from a polyimide resin and a rewiring pattern formed on the insulating film 16, respectively.